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Thursday, January 12, 2017

Management of May–Thurner Syndrome in Adolescents

Although there is a mature body of evidence supporting the safety and efficacy of endovascular intervention for May-Thurner syndrome (MTS) in adults, few studies have described results of intervention in the pediatric population. Goldman et al present a retrospective, single institution study of 10 adolescent patients, ages 12-18 years, who underwent endovascular therapy for MTS between 1998 and 2015. Six patients had pro-thrombotic risk factors including heritable conditions like factor V Leiden and/or oral contraceptive use. Acute deep venous thrombosis (DVT) was the presentation of 6/10 patients, who were treated with catheter-directed thrombolysis (CDT) alone or in combination with pharmacomechanical thrombolysis. The remaining 4/10 presented with symptoms of chronic venous outflow obstruction. All patients (thrombotic and non-thrombotic) were treated with venoplasty and stenting. Stent models included S.M.A.R.T, Wallstent, and Protégé stents, varying between 12-mm-16-mm diameters. Thrombolysis was technically successful in 4/5 patients and stenting was technically successful in 9/10 patients (the last patient did not have available imaging for review). No periprocedural complications were observed. All patients were treated with systemic anticoagulation for at least 3-months following intervention and were followed for median 32-months (range: 6-109 months). The rates of post-thrombotic syndrome (PTS) following intervention was 0% by Villalta score and 60% by modified Villalta score (designed for use in the pediatric population), and all cases with positive PTS were mild in symptom severity. Iliofemoral patency rates at 12-months were 79% (primary) and 100% (secondary), and at 36-months were 79% (primary) and 89% (secondary). One patient with antiphospholipid syndrome and homozygous MTHFR gene mutation, as well as non-adherence to medical anticoagulation presented with occlusive thrombus 14-months after initial intervention, but no invasive therapy was pursued given relatively mild symptoms.

Commentary

Venothromboembolism (VTE) is rare in the pediatric population, and pediatric MTS therefore remains a nascent area of study, for which optimal therapeutic approach is not fully elucidated. The risks for recurrent DVTs, and long-term debility from PTS in the adult MTS population has been well described, and pediatric patients may suffer similar outcomes without treatment. The experience described by Goldman et al suggests that CDT and stenting techniques may be applied with similar efficacy and safety in the adolescent population as the adult population, suggesting that these techniques should be considered in these patients. In particular, the high primary and secondary patency rates at 12 and 36-months compare favorably to those reported in adults. The authors highlighted the challenges to stenting MTS patients with underlying thrombophilic syndromes, which overall had poorer patency outcomes than those without thrombophilic syndromes and included a case of re-occlusion associated with prothromobotic syndrome and non-compliance with anticoagulation regimen. The study was subject to biases of a small patient population, retrospective imaging and clinical assessment, and non-standardized anticoagulation regimens as well as follow-up times. Furthermore, the majority of patients were of adult body habitus so the endovascular techniques and venous patency outcomes cannot be generalized to younger pediatric patients, who still have significant growth potential. Nonetheless, this study bolsters the limited evidence base for endovascular management of MTS in the pediatric population by demonstrating excellent long-term patency rates and safety profile, concordant with results seen in adults and further follow-up studies would be beneficial.